The influence of repeated oral administration of dichlorvos on circulating esterases in buffalo calves (Bubalus bubalis)

Alterations in circulating esterases induced by dichlorvos and their reversibility were investigated in male buffalo calves. Changes in blood glucose and total plasma proteins were also monitored. Animals received 4 or 8 mg dichlorvos/kg/day po for 28 consecutive d. Dichlorvos caused dose- and time- dependent significant (P less than 0.01) inactivation of blood esterases. Maximal inhibition of plasma cholinesterase (87-94%) and serum carboxylesterase (51-67%) was observed on the 28th day. An increase in blood glucose and total plasma proteins occurred during the dosing period; these parameters returned to control values in surviving animals within 7 d after the final dose. Activities of esterases returned to 45-70% of normal the 14th d after cessation of dichlorvos dosing.